Use CADET C-API

[schmoelder]

Previously, CADET could only save simulation results to a file. However, this requires a lot of overhead and the IO can be limiting when many simulations are run (e.g. in optimization studies but also when many cycles need to be simulated to reach cyclic stationarity).
With its new C-API (still WIP), CADET also allows reading results from memory.

For this purpose, the methods for the following steps need to be implemented in CADET-Python and CADET-Process:

• initialize simulator
• set parameters
• run simulator
• read results

There still seem to be some small issues in CADET-Core / Python that need to be fixed before properly testing the C-API in CADET-Process:

• Inconsistencies between interface specification / CLI-interface / C-API cadet/CADET-Core#334
• https://github.com/cadet/CADET-Python/pull/42/files
  However, I'm relatively confident that there will not be major issues.

[schmoelder]

I think, this is generally ready but we should test it again.